Messages in this thread | | | Subject | Re: [PATCH] isdn: mISDN: tei: Fix a sleep-in-atomic-context bug in create_teimgr() | From | isdn@linux-pi ... | Date | Sun, 2 Sep 2018 18:31:07 +0200 |
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Hi,
I do not understand the analysis and do not see that the spinlock is a problem here. I think your DSAC analyzer assumes that the FUNC_PTR mgr_ctrl call calls the mgr_ctrl in tei.c, but in real it calls l2->ch.ctrl() which is the function in layer2.c, not tei.c. And the function in layer2.c should not do any GFP_KERNEL allocation.
Same for your 2. reported issue.
Am 01.09.2018 um 14:00 schrieb Jia-Ju Bai: > The kernel module may sleep with holding a spinlock. > > The function call paths (from bottom to top) in Linux-4.16 are: > > [FUNC] kzalloc(GFP_KERNEL) > drivers/isdn/mISDN/tei.c, 1058: kzalloc in create_teimgr > drivers/isdn/mISDN/tei.c, 1278: create_teimgr in mgr_ctrl > drivers/isdn/mISDN/tei.c, 1048: [FUNC_PTR]mgr_ctrl in create_teimgr > drivers/isdn/mISDN/tei.c, 1045: _raw_read_lock_irqsave in create_teimgr > > Note that [FUNC_PTR] means a function pointer call is used. > > To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC. > > This bug is found by my static analysis tool DSAC. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > drivers/isdn/mISDN/tei.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/isdn/mISDN/tei.c b/drivers/isdn/mISDN/tei.c > index 12d9e5f4beb1..6d95ee639fdb 100644 > --- a/drivers/isdn/mISDN/tei.c > +++ b/drivers/isdn/mISDN/tei.c > @@ -1055,7 +1055,7 @@ create_teimgr(struct manager *mgr, struct channel_req *crq) > crq->adr.tei, crq->adr.sapi); > if (!l2) > return -ENOMEM; > - l2->tm = kzalloc(sizeof(struct teimgr), GFP_KERNEL); > + l2->tm = kzalloc(sizeof(struct teimgr), GFP_ATOMIC); > if (!l2->tm) { > kfree(l2); > printk(KERN_ERR "kmalloc teimgr failed\n"); >
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